Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.

https://hal.archives-ouvertes.fr/hal-01209876/document

A standardised static in vitro digestion method suitable for food – an international consensus

The growing need for Lactobacillus bacteria usage in industry and the expending probiotic market led to a search for new cost-efficient fermentation media from which a high yield of these bacteria could be obtained. The following study aimed to elaborate cultivation medium, for Lactobacillus spp. growth, which main components would be wheat, maize, barley, and rye flours. The optimal temperature for Lactobacillus growth in new semi-solid fermentation (SSF) medium, water content, and pH of the medium were analyzed by the plate count method. It was established, that the highest bacteria counts were obtained from cultures conducted in the SSF medium with flours to water ratio of 1:1.5 with a natural pH of 6.0 at 37 °C. Subsequently, the growth kinetics of analyzed strains, in both MRS and the SSF media, were studied. The newly designed media contributed to the increased duration of selected Lactobacillus strains lag phase, which varied from 1.98 to 5.64; nevertheless, the maximum growth rate of the strains was two times higher in the SSF medium rather than in MRS, which also resulted in shorter generation time. The developed medium has the potential to become a new cost-efficient fermentation medium for Lactobacillus spp.

https://www.mdpi.com/2079-7737/9/12/423/pdf

Growth Kinetics of Probiotic Lactobacillus Strains in the Alternative, Cost-Efficient Semi-Solid Fermentation Medium.

Bifidobacterium is a common probiotic that plays a vital role in the intestinal tract. This study aimed to explore the different effects of soybean protein and soybean peptides on the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190. Soybean protein and soybean peptides were digested in vitro, after which different nitrogen source containing media were prepared and used for the monoculture of Bifidobacterium animalis subsp. animalis JCM 1190 and the co-culture of Bifidobacterium animalis subsp. animalis JCM 1190 and Escherichia coli JCM 1649. During the culture process, the viable cell number and lactic acid and acetic acid contents were measured, while non-targeted metabonomics was used to detect the differential metabolites and metabolic pathways. The results showed that soybean protein and soybean peptides promoted the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190, while digested soybean peptides had a better effect. Digested soybean peptides increased the viable cell number and lactic acid and acetic acid contents in the monoculture by regulating glycine, serine, and threonine metabolism, as well as pyruvate metabolism, the TCA cycle, glycolipid metabolism, and other metabolic pathways, balanced the ability of Bifidobacterium animalis subsp. animalis JCM 1190 and Escherichia coli JCM 1649 to utilize nitrogen sources during the early period and enhanced the competitiveness of Bifidobacterium animalis subsp. animalis JCM 1190 during the later period in co-culture.

Different effects of soybean protein and its derived peptides on the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190.

Specific soil bacteria can sense and respond to the selective rhizosphere recruitment of root exudates using unique systems of chemotaxis that mediate plant-microbe and microbe-microbe interactions. This study investigates how the bacterial chemotaxis systems have been impacted by selection during the domestication of rice (Oryza species). Shotgun metagenomic sequencing and 16S rRNA gene amplicon sequencing were performed to investigate the bacterial chemotaxis systems and chemotactic bacteria in the rhizospheres of wild and cultivated rice. Metabolomics analysis was performed to examine the root metabolites of different accessions of rice. The bacterial chemotaxis genes exhibited a higher abundance in the rhizospheres of wild rice than cultivated rice, and that the compositional profile of chemotaxis genes was distinctly different between types of rice. Differential selection of chemotaxis systems was at least partially driven by changes in the metabolite profiles of rice roots that were affected by domestication. A core group of chemotactic bacteria was also identified, and specific chemotactic bacteria were found to function as hub taxa in the rhizosphere bacterial community. The present study provides novel insights into the composition and function of the bacterial chemotaxis systems in the rhizospheres of wild and domesticated rice. It also provides a new perspective on the impact of rice domestication on the assembly of rhizomicrobiome.

Rice domestication influences the composition and function of the rhizosphere bacterial chemotaxis systems

Pectin recovered from mango peel biomass can be used as a potential source for pectic oligosaccharide hydrolysate with excellent probiotic growth-enhancing performance and prebiotic potentials. Consequently, the objectives of the current study were to optimise the enzyme hydrolysis treatment of mango peel pectin (MPP) and to evaluate the pectic oligosaccharide effects of Lactobacillus reuteri DSM 17938 and Bifidobacterium animalis TISTR 2195. Mango of "chok anan" variety was chosen due to its excessive volume of biomass in processing and high pectin content. The optimal treatment for mango peel pectic oligosaccharide (MPOS) valorisation was 24 h of fermentation with 0.3% (v/v) pectinase. This condition provided small oligosaccharides with the molecular weight of 643 Da that demonstrated the highest score of prebiotic activity for both of B. animalis TISTR 2195 (7.76) and L. reuteri DSM 17938 (6.87). The major sugar compositions of the oligosaccharide were fructose (24.41% (w/w)) and glucose (19.52% (w/w)). For the simulation of prebiotic fermentation, B. animalis TISTR 2195 showed higher proliferation in 4% (w/v) of MPOS supplemented (8.92 log CFU/mL) than that of L. reuteri (8.53 CFU/mL) at 72 h of the fermentation time. The main short chain fatty acids (SCFAs) derived from MPOS were acetic acid and propionic acid. The highest value of total SCFA was achieved from the 4% (w/v) MPOS supplementation for both of B. animalis (68.57 mM) and L. reuteri (69.15 mM). The result of this study therefore conclusively advises that MPOS is a novel pectic oligosaccharide resource providing the opportunity for the sustainable development approach through utilising by-products from the fruit industry.

Crude Pectic Oligosaccharide Recovery from Thai Chok Anan Mango Peel Using Pectinolytic Enzyme Hydrolysis.

Soybean protein (Pro) and soybean oligopeptide (Pep) were subjected to simulated digestion in vitro to study the effect of Pep on the growth and metabolism of Lactobacillus acidophilus JCM 1132. First, the molecular weight distribution differences of samples before and after digestion were compared, and the samples were used to replace the nitrogen source components in the culture media. Then, the viable cell numbers, lactic acid and acetic acid content, differential metabolites, and metabolic pathways during the culturing process were measured. Results showed that the digested soybean oligopeptide (dPep) was less efficient than MRS medium in promoting the growth, but by increasing the content of the intermediates during the tricarboxylic acid (TCA) cycle, its metabolic capacity was significantly improved. Besides, due to the low molecular weight of dPep, it can be better transported and utilized. And dPep significantly strengthened the amino acid metabolism and weakened the glycerol phospholipid metabolism, so the ability of dPep in promoting the growth and metabolism of Lactobacillus acidophilus JCM 1132 is higher than the digested soybean protein (dPro).

/pdf/effect-of-soybean-oligopeptide-on-the-growth-and-metabolism-143m6n9w5c.pdf

Jalal Uddin

Papers

Effect of soybean oligopeptide on the growth and metabolism of Lactobacillus acidophilus JCM 1132